Research has demonstrated that both violent victimization and neighborhood context influence youth development. However, the ways in which these factors individually and jointly affect the development of substance use is unclear. The goal of this study is to examine the relationship between violent victimization, neighborhood context and drug use from adolescence (ages 12-18) through early adulthood (ages 15 to 21). To do so, the project will analyze longitudinal data from the Project on Human Development in Chicago Neighborhoods (PHDCN), a large-scale study specifically designed to investigate contextual effects on individual development. We examine three aims in this study: 1) the effects of violent victimization on youth substance use, including a comparison of direct (i.e., personally experiencing violence) and indirect (i.e., witnessing violence committed against another) victimization;2) the effects of neighborhood structural (i.e., concentrated disadvantage) and social (i.e., collective efficacy, social ties, and cultural norms regarding adolescent substance use and delinquency) characteristics on youth drug use;and 3) the extent to which neighborhood context moderates the effects of victimization on youth substance use. Examination of these issues can help inform prevention efforts designed to reduce the initiation and progression of adolescent substance use. Identifying youth most at risk for engaging in substance use (e.g., such as those exposed to violent victimization or living in disadvantaged communities) will allow services to be targeted to those most in need. In addition, if neighborhood characteristics are shown to influence the relationship between victimization and substance use, neighborhood-level interventions would be suggested to enhance features of the community (e.g., to foster higher levels of informal social control or trust between neighbors) in order to reduce drug use. PUBLIC HEALTH RELEVANCE: The public health benefits of the proposed research project will include increasing our understanding of the ways in which violent victimization and neighborhood characteristics may independently and jointly affect the likelihood of drug use during adolescence. Results from this study can inform community-based prevention efforts intended to delay or reduce adolescent drug use.